Cl-chacha



United States Patent Ofiice 3,123,450 Patented Mar. 3, 1964 3,123,450 MOTOR FUEL John P. Buckmann, Yorba Linda, Caliil, assignor to Union Gil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Filed Feb. 13, 1959, Ser. No. 792,957 9 Claims. (Cl. 44-69) This invention relates to motor fuels, especially gasolines, containing tetraethyl lead (TEL), plus a preignition additive, i.e., an additive for reducing preignition of the fuel.

TEL has been in commercial use for many years in gasolines for the purpose of preventing detonation knocking, i.e., knocking which occurs after the ignition of the air-fuel mixture by firing of the spark. Unfortunately the lead forms deposits in the combustion chamber, along with carbonaceous deposits, and it is thought that the lead serves to lower the temperature at which the carbonaceous material ignites sufliciently to glow and thereby ignite the fuel. In other Words, it is inevitable that there will be some carbonaceous deposits, from both the fuel and the oil, in the combustion chamber of an internal combustion engine; and if these deposits ignite or glow, or for any reason remain hot enough to ignite the next charge of fuel introduced into the cylinder, preignition (ignition prior to spark ignition) will occur. This preignition has a number of bad effects. It may decrease power; it may produce a rumble or ping noise which is not only objectionable from the standpoint of smoothness and quietness of operation, but probably also reduces the life of the engine; and in some cases in which it is so severe as to become uncontrolled, it Will melt a hole in the piston. While the difficulties have been experienced chiefly in aircraft engines, modern automobile engines of high compression ratio and high power output are experiencing almost as much trouble from this source as from the detonation-type of knocking. Present aircraft fuels contain up to about 6 ml. of TEL per gallon, and automotive fuels contain up to about 3 ml. of TEL per gallon.

A test for preignition has been devised, which will be described hereinafter in more detail. Briefly, it involves measuring the number of flames in a given cycle, which occur in the combustion chamber prior to the time at which the normal flame induced by the spark occurs. The efliciency of a preignition additive can be measured by the preignition index, which is the percent of such abnormal flames occurring in the additive-contaning test gasoline as compared with the base fuel, i.e., the same TEL-containing gasoline containing no preignition additive.

It is an object of this invention to provide a motor fuel containing a preignition additive and TEL in amounts suflicient to substantially reduce the detonation knocking as well as preignition; i.e., to provide a TEL-containing motor fuel of low preignition index. Other objects will appear in the following description of the invention.

Briefly, the invention comprises adding to a TEL- containing motor fuel, particularly a fuel consisting essentially of hydrocarbons in the gasoline boiling range, i.e., between about 50 -F. and about 4'50=-500 -F., an organic phosphine borine or phosphino borine as hereinafter described, in an amount not substantially greater than about 1.0 theory B or 3.0 theory P, 1.0 theory P being the theoretically minimum amount of additive required to convert all of the lead contained in the TEL to lead phosphate, Pb (PO- and 1.0 theory B being the theoretically minimum amount of additive required to convert the lead of the TEL to lead meta borate, Pb(BO This minimum amount of additive is calculated on the assumption that all of the phosphorus or boron in the additive is used to react with the lead.

Although preignition is thought to result from the use in an engine of a gasoline containing lead, preignition is observed with non-leaded fuels. Additives, other than those containing lead, as well as certain types of hydrocarbons, e..g., naphthalene, alkylated naphthalenes and other condensed ring aromatic compounds, may cause deposits in combustion chambers which do tend to glow, particularly under extreme conditions of operation, and may result in preignition occurring during the engine operation. Fuels of this type, as well as those fuels containing TEL, may be said to be preignition-prone fuels. The tendency for preignition to occur in such fuels which do not contain lead but which are preignition-prone can also be overcome by the use of the organic phosphine borines or organic phosphin'o borines described herein as being useful in connection With leaded fuels. The amount of halogen-containing phosphine borine or phosphino borine to be used in such fuels which do not contain lead will generally be not more than that amount corresponding to 1.0 theory of 'B or 3.0 theory of P calculated on the basis that the fuel contained 3 ml. of TEL.

The organic phosphine borines of this invention are halogenated compounds and thus may be more correctly described as organo halo phosphine borines. These compounds have the general formula in which X to X represent hydrogen, halogen, monovalent hydrocarbon or monovalent halohydrocarbon groups, at least one of said X groups containing at least one halogen atom; R to R represent hydrogen, hydrocarbon or halohydroca-rbon groups, said hydrocarbon and halohydrocarbon groups being monovalent or bivalent, in which two of said R groups represent a single bivalent hydrocarbon group; and R may represent a bis-group as follows:

in which X to X and R and R are as above defined, and in which R is a bivalent group of 3 to 10 carbon atoms selected from the class consisting of unsubstituted and halogenated alkylene groups. The compounds in which R is a bis-group are referred to herein as hiscompounds.

In the above formulas and definitions, the term hydrocarbon group is used in itsusual sense to mean an alkyl, cycloalkyl, aryl, aralkyl or alkaryl radical containing only carbon and hydrogen. The term halohydrocarbon group means any of the mentioned hydrocarbon groups which contain at least one halogen atom and preferably not more than about 3 halogen atoms. Each of said hydrocarbon or halohydrocarbon groups will contain 1 to 10 and preferably 1 to about 4 carbon atoms. Where two R groups represent a single bivalent hydrocarbon group, this group may be an alkylene forming with the phosphorus atom a polymethylene ring containing 3 to 6 carbon atoms. This group may or may not contain halogen. As used throughout this specification and in the claims, halogen has its usual meaning and includes fluorine, chlorine, bromine and iodine. The fluorine and chlorine compounds are preferred and fluorine compounds are particularly preferred.

In the above phosphine borine compounds, the ratio of halogen atoms to phosphorus atoms will not be greater than 6 to 1 and preferably not greater than about 4 to 1.

The organic phosphine borines of this invention are halogenated compounds and thus may be referred to as organic halo phosphino borines. They may further be defined as condensation polymers of the above described phosphine borines. They are formed by simple dehydrogenation or dehydrohalogenation of appropriate monomers. Their formation can take place with or without cyclization. Where cyclization does not occur compounds having the following general formula are obtained.

i r i r r r -(r rr X: R: X3 R2 11X: R2

in which n is to and the X and R groups are as defined above in connection with the general formula for phos phine borines.

The cyclic polymers having 6 or 8 membered rings are preferred over the linear polymers. Such compounds have the following formulas:

The bonds shown in these formulas are satisfied by the Rand X groups as defined in connection with the formula for the phosphine borines. At least one of the groups attached to each boron atom will contain or consist of a halogen atom.

The above described organic halo phosphine borines and organic halo phosphine borines of this invention will preferably have molecular weights less than about 1500 and preferably less than about 1000. They are all free from substituents other than halogen or hydrocarbon substituents, and thus consist of phosphorus, boron, carbon, hydrogen and halogen.

It should be pointed out that neither the nomenclature nor the structural formulas of any of the above described phosphorus-boron compounds is clearly established. However, the terminology used herein is believed to be clear and agrees with the terminology employed by many investigators in this field. Also, the bond between the phosphorus and the boron shown in the above structures is not a single bond or a typical olefin double bond or even a typical double bond of an aromatic hydrocarbon structure. It is probably simply a shared electron pair. Regardless of the nature of the bonds between the P and B atoms, however, the structural formulas of these compounds are believed to be as shown.

The compounds of this invention are made rather simply. The compounds in which X X and X; are all chlorine, for example, are made by reacting boron trichloride, B01 with an appropriate organic phosphine. The compounds in which one or two of the X to X groups are hydrocarbon or halogenated hydrocarbon groups may be prepared by substituting the alkyl or aryl monochloroor dichloro-boranes for the boron trichloride. These alkyl or aryl halo-boranes are prepared by various methods, such as those described in Bulls et al., J.A.C.S. 79, 337, or McCusker et al., I .A.C.S. 79', 5182. The organic phosphines are made by reacting an alkyl or aryl halide or polyhalide in liquid ammonia solution with sodium and white phosphorus to form a sodium alkyl or aryl (or halogenated alkyl or aryl) phosphide, which in turn is reacted with hydrogen chloride or alkyl or aryl halide or polyhalide to form the organic phosphine. Numerous other methods of preparation are summarized by Kosalopotf, Organic Phosphorus Compounds, John Wiley and Sons, New York, 1950.

As an example of the preparation of the compounds of this invention, if the compound tribu-tylphosphine ethyldichloroborine, hereinafter called simply EDC, is desired, sodium, white phosphorus and n-butyl chloride are reacted in liquid ammonia solution to form sodium di-butyl phosphide. This in turn is reacted with additional n-butyl chloride to form tribntyl-phosphine. This latter compound is then reacted with ethyldichloroborane (prepared as described by McCusker et al., supra) to form the desired compound. Thus, this compound is an example of the general formula in which R to R are each n-butyl; X is ethyl; and X and X, are chlorine.

As a specific example of the invention, tributylphosphine-ethyldichloroborine was added to a commercial premium gasoline having a motor octane number of 88.1, a research octane number of 98.7, an API gravity of 56.0, a sulfur content of 0.090% and a nitrogen content of 0.007%. This gasoline contained 3.06 ml./ gallon of TEL. The amount of phosphine borine compound used amounted to 0.96 g./gal., or 0.3 theory of P. This gasoline was found to have a preignition index of 31 in the preignition test described hereinabove.

To show how this compares with other commercially and experimentally available gasoline additives containing phosphorus or boron, the following data were obtained:

Table Preigni- Fuel Additive and Concentration tion Index, Percent Phosphorus Compounds:

0.3 Theory P as Comml Additive A 64 0.6 Theory P as Comml Additive A 36 1.0 Theory P as Comml Additive A 31 0.3 Theory P as Gomml Additive B.. 57 0.3 Theory P as Comml Additive C 50 0.3 Theory 1? as Comml Additive D. 57 Boron Compounds:

0.46 Theory B as Comml Additive E 119 0.2 Theory B as Experimental Additive F Boron-i-Phosphorus Additive Mixture:

0.3 Theory P as Additive A plus 78 0.1 Theory B as Additive E Tributylph osphine-ethyldichlorobor 0.3 Theory P 81 As further examples of this invention, the following halogen-containing phosphine borines and phosphino borines when added to gasoline with or without lead and preferably containing up to about 6 ml. of TEL per gallon in amounts corresponding to between about 0.05 and about 3.0 theory of phosphorus decrease the preignition index of the gasoline.

Tributylphosphine ethyldifluoroborine Tributylphosphine ethyldibromoborine T ributylphosphine trifiuoroborine Tributylphosphine trichloroborine Tributylphosphine-diethyl-chloroborine Cl-GHqCHgCHg CH3 Cl-O H H 0 H;P=B C Ha Cl-OHaCHsCH: CH:

Tris-3- chloropropylph o sphine-trimethylb 'o tine Cl-C H2 C H2 C1 C1CHzCHz-P=BCl (ll-CHzOHa Cl Tr1s-2-chloroethylphosphine-trichloroborine CH3 CH3 Dimethylphosphino difluoroborine cyclic trimer 0 H: F CHa P=BF C H: CaHs Trimethylphosphine-ethyldifluoroborine O HZC Hz 0 H: C H2 p-Bromophenyl-tetramiethylene ph osphine borine o-Chloroplrenyl pentamethylene phosphine trlmethylborine Other modifications of the invention which would occur to one skilled in the art are to be considered within the scope of the invention as defined in the following claims.

I claim:

1. A motor fuel consisting essentially of hydrocarbons boiling in the gasoline range and containing an antiknock quantity of a tetra-alkyl lead and a small amount, suf- 6 ficient to reduce the preignition tendency of said hydrocar-bons, of a compound having the general formula:

wherein n is a value selected from the group consisting of 0 and :l and m is a value selected from the group consisting of 3, 1 and O, m being selected from the class consisting of 0 and. 1 when n is 1, and m being 3 when n is 0; wherein each R represents a substituent selected from the class consisting of. hydrogen, halogen, and alkyl radicals containing from 1 to 8 carbon atoms, at least one of said R substituents being halogen; and wherein each R represents a substituent selected from the class consisting of hydrogen, alkyl radicals and aryl radicals, at least one of said R groups being selected from the class consisting of alkyl radicals and aryl radicals, and, when n is 0 and m is 3, one of said R groups may be a his group having the formula:

RIIIRII2P, BR I,3

wherein R' represents an alkylene group, each R" represents a substituents selected from the class consisting of hydrogen, alkyl radicals and aryl radicals, and each R represents a substituent as hereinbefore defined.

2. A motor fuel according to claim 1 in which sald compound is a trimer containing at least one ring of the following type:

3. A motor fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range containing not more than about 6 ml. per gallon of TEL and a small amount, suflicient to reduce the preignition tendency of said fuel, of an organic phosphine borine having the formula in which X to X, each represent a radical of the class consisting of hydrogen, halogen, monovalent hydrocarbon and monovalent halohydrocarbon radicals in which at least one of said X groups contains at least one halogen atom; R to !R represent (1) a radical of the class consisting of hydrogen, hydrocarbon and halohydrocarbon radicals, (2) two of said R groups represent divalent hydrocarbon and divalent halohydrocarbon groups, and (3) R may also represent a bis-group RP=BX in which R R and X to X are as above defined and R is a bivalent group of 3 to 10' carbon atoms selected from the class consisting of unsubstituted and halogenated alkylene radicals; said hydrocarbon radicals being selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl and alkaryl radicals and said halohydrocarbon radicals being hydrocarbon radicals containing 1 to 3 halogen atoms per radical, said hydrocarbon radicals and said halohydrocarbon radicals each containing 1 to 10 carbon atoms.

4. A motor fuel according to claim 3 in which said halogen is chlorine.

5. A motor fuel according to claim 3 in which said halogen is fluorine.

6. A motor fuel according to claim 3 in which each of said hydrocarbon and halohydrocarbon groups contain not more than about 4 carbon atoms.

7. A motor fuel according to claim 3 in which X X and X each represent halogen.

8. A motor fuel according to claim 3 in which R and R represent a single bivalent polymethylene radical.

9. A motor fuel consisting essentially of hydrocarbons boiling in the gasoline boiling range containing not more than about 6 ml. per gallon of TEL and a small amount, sufficient to reduce the preignition tendency of said fuel, of tributylphosphine-ethyldichloroborine.

References Cited in the file of this patent 8 Bereslavsky June 25, 1957 Scott et a1 Jan. 218, 1958 Stewart et a1 Mar. 24, 1959 Groszos et a1. June 30, 1959 FOREIGN PATENTS Great Britain May 14, 1958 OTHER REFERENCES Chemical Reviews, Vol. 5 8, N0. 1, February 1958,

Stability Relationships Among Analogous Molecular Addition Compounds of Group III Elements, by Stone, pages 101-129, photocopy in 260-60 6. 5. 

1. A MOTOR FUEL CONSISTING ESSENTIALLY OF HYDROCARBONS BOILING IN THE GASOLINE RANGE AND CONTAINING AN ANTIKNOCK QUANTITY OF A TETRA-ALKYL LEAD AND A SMALL AMOUNT, SUFFICIENT TO REDUCE THE PREIGNITION TENDENCY OF SAID HYDROCARBONS, OF A COMPOUND HAVING THE GENERAL FORMULA: 